clock kept step with the seasonal
variation of the times of sunrise and sunset and the lengths of day and
night.

The anaphoric clock is not only the origin of the astrolabe and of all
later planetary models, it is also the first clock dial, setting a
standard for "clockwise" rotation, and leaving its mark in the rotating
dial and stationary pointer found on the earliest time-keeping clocks
before the change was made to a fixed dial and moving hand.

We come finally to a piece of archaeological evidence that surpasses all
else. Though badly preserved and little studied it might well be the
most important classical object ever found; entailing a complete
re-estimation of the technical prowess of the Hellenistic Greeks. In
1901 a sunken treasure ship was discovered lying off the island of
Antikythera, between Greece and Crete.[16] Many beautiful classical
works of statuary were recovered from it, and these are now amongst the
greatest treasures of the National Museum at Athens, Greece. Besides
these obviously desirable art relics, there came to the surface some
curious pieces of metal, accompanied by traces of what may have been a
wooden casing. Two thousand years under the sea had reduced the metal to
a mess of corroded fragments of plates, powdered verdigris, and still
recognizable pieces of gear wheels.

If it were not for the established dates for other treasure from this
ship, especially the minor objects found, and for traces of inscriptions
on this metal device written in letters agreeing epigraphically with the
other objects, one would have little doubt in supposing that such a
complicated piece of machinery dated from the 18th century, at the
earliest. As it is, estimates agree on _ca._ 65 B.C. +-10 years, and we
can be sure that the machine is of Hellenistic origin, possibly from
Rhodes or Cos.

[Illustration: Figure 6.--ANTIKYTHERA MACHINE, LARGEST FRAGMENT. (_Photo
courtesy of National Museum, Athens._)]

The inscriptions, only partly legible, lead one to believe that we are
dealing with an astronomical calculating mechanism of some sort. This is
born out by the mechanical construction evident on the fragments. The
largest one (fig. 6) contains a multiplicity of gearing involving an
annular gear working epicyclic gearing on a turntable, a crown wheel,
and at least four separate trains of smaller gears, as well as a
4-spoked driving wheel. One of the smaller fragments (fig. 7, bottom)
contains a series of